88 lines
2.1 KiB
Go
88 lines
2.1 KiB
Go
// Copyright 2010 The Freetype-Go Authors. All rights reserved.
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// Use of this source code is governed by your choice of either the
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// FreeType License or the GNU General Public License version 2 (or
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// any later version), both of which can be found in the LICENSE file.
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package main
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import (
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"bufio"
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"fmt"
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"image"
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"image/draw"
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"image/png"
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"log"
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"os"
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"freetype-go.googlecode.com/hg/freetype/raster"
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)
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func p(x, y int) raster.Point {
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return raster.Point{raster.Fix32(x * 256), raster.Fix32(y * 256)}
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}
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func clear(m *image.Alpha) {
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b := m.Bounds()
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for y := b.Min.Y; y < b.Max.Y; y++ {
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base := y * m.Stride
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p := m.Pix[base+b.Min.X : base+b.Max.X]
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for i, _ := range p {
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p[i] = image.AlphaColor{0}
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}
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}
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}
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func main() {
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// Draw a rounded corner that is one pixel wide.
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r := raster.NewRasterizer(50, 50)
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r.Start(p(5, 5))
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r.Add1(p(5, 25))
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r.Add2(p(5, 45), p(25, 45))
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r.Add1(p(45, 45))
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r.Add1(p(45, 44))
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r.Add1(p(26, 44))
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r.Add2(p(6, 44), p(6, 24))
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r.Add1(p(6, 5))
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r.Add1(p(5, 5))
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// Rasterize that curve multiple times at different gammas.
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const (
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w = 600
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h = 200
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)
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rgba := image.NewRGBA(w, h)
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draw.Draw(rgba, image.Rect(0, 0, w, h/2), image.Black, image.ZP, draw.Src)
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draw.Draw(rgba, image.Rect(0, h/2, w, h), image.White, image.ZP, draw.Src)
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mask := image.NewAlpha(50, 50)
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painter := raster.NewAlphaSrcPainter(mask)
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gammas := []float64{1.0 / 10.0, 1.0 / 3.0, 1.0 / 2.0, 2.0 / 3.0, 4.0 / 5.0, 1.0, 5.0 / 4.0, 3.0 / 2.0, 2.0, 3.0, 10.0}
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for i, g := range gammas {
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clear(mask)
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r.Rasterize(raster.NewGammaCorrectionPainter(painter, g))
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x, y := 50*i+25, 25
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draw.DrawMask(rgba, image.Rect(x, y, x+50, y+50), image.White, image.ZP, mask, image.ZP, draw.Over)
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y += 100
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draw.DrawMask(rgba, image.Rect(x, y, x+50, y+50), image.Black, image.ZP, mask, image.ZP, draw.Over)
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}
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// Save that RGBA image to disk.
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f, err := os.Create("out.png")
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if err != nil {
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log.Println(err)
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os.Exit(1)
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}
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defer f.Close()
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b := bufio.NewWriter(f)
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err = png.Encode(b, rgba)
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if err != nil {
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log.Println(err)
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os.Exit(1)
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}
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err = b.Flush()
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if err != nil {
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log.Println(err)
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os.Exit(1)
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}
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fmt.Println("Wrote out.png OK.")
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}
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